I want to decorate a cake in buttercream but I want it to be brown so I was thinking doing a chocolate buttercream. I also want to use Indydebi's crisco based buttercream. Howmuch Hershey's cocoa powder do I add in the recipe? Am I supposed to omit some of the powdered sugar to be able to use the cocoa powder? Thanks!
I don't measure, I just Add to taste, no need to eliminate PS, unless you want to--may need a little more liquid to get to the right consistency. Trial and error usually works best 
Also, depending on how "brown" you need your buttercream, may decide how much cocoa you need. HTH
You can also get a darker brown (pretty darn close to black even) if you use Hershey's special dark cocoa. If you need something in between, adjust how much reg. cocoa powder you use and how much of the special dark.
A couple of examples from a friend of mine:
http://cakeideas.blogspot.com/search/label/Hershey%27s%20Special%20Dark%20cocoa
HTH
also using chocolate milk gives it an extra kick.
xx
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